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Gąsiorowski L, Dittmann IL, Brand JN, Ruhwedel T, Möbius W, Egger B, Rink JC. Convergent evolution of the sensory pits in and within flatworms. BMC Biol 2023; 21:266. [PMID: 37993917 PMCID: PMC10664644 DOI: 10.1186/s12915-023-01768-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Accepted: 11/13/2023] [Indexed: 11/24/2023] Open
Abstract
BACKGROUND Unlike most free-living platyhelminths, catenulids, the sister group to all remaining flatworms, do not have eyes. Instead, the most prominent sensory structures in their heads are statocysts or sensory pits. The latter, found in the family Stenostomidae, are concave depressions located laterally on the head that represent one of the taxonomically important traits of the family. In the past, the sensory pits of flatworms have been homologized with the cephalic organs of nemerteans, a clade that occupies a sister position to platyhelminths in some recent phylogenies. To test for this homology, we studied morphology and gene expression in the sensory pits of the catenulid Stenostomum brevipharyngium. RESULTS We used confocal and electron microscopy to investigate the detailed morphology of the sensory pits, as well as their formation during regeneration and asexual reproduction. The most prevalent cell type within the organ is epidermally-derived neuron-like cells that have cell bodies embedded deeply in the brain lobes and long neurite-like processes extending to the bottom of the pit. Those elongated processes are adorned with extensive microvillar projections that fill up the cavity of the pit, but cilia are not associated with the sensory pit. We also studied the expression patterns of some of the transcription factors expressed in the nemertean cephalic organs during the development of the pits. Only a single gene, pax4/6, is expressed in both the cerebral organs of nemerteans and sensory pits of S. brevipharyngium, challenging the idea of their deep homology. CONCLUSIONS Since there is no morphological or molecular correspondence between the sensory pits of Stenostomum and the cerebral organs of nemerteans, we reject their homology. Interestingly, the major cell type contributing to the sensory pits of stenostomids shows ultrastructural similarities to the rhabdomeric photoreceptors of other flatworms and expresses ortholog of the gene pax4/6, the pan-bilaterian master regulator of eye development. We suggest that the sensory pits of stenostomids might have evolved from the ancestral rhabdomeric photoreceptors that lost their photosensitivity and evolved secondary function. The mapping of head sensory structures on plathelminth phylogeny indicates that sensory pit-like organs evolved many times independently in flatworms.
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Affiliation(s)
- Ludwik Gąsiorowski
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.
| | - Isabel Lucia Dittmann
- Institut Für Zoologie, Universität Innsbruck, Technikerstraße 25 6020, Innsbruck, Austria
| | - Jeremias N Brand
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany
| | - Torben Ruhwedel
- Electron Microscopy Facility, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, City Campus, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Wiebke Möbius
- Electron Microscopy Facility, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, City Campus, Hermann-Rein-Str. 3, 37075, Göttingen, Germany
| | - Bernhard Egger
- Institut Für Zoologie, Universität Innsbruck, Technikerstraße 25 6020, Innsbruck, Austria
| | - Jochen C Rink
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.
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Brand JN. Support for a radiation of free-living flatworms in the African Great Lakes region and the description of five new Macrostomum species. Front Zool 2023; 20:31. [PMID: 37670326 PMCID: PMC10478486 DOI: 10.1186/s12983-023-00509-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 08/14/2023] [Indexed: 09/07/2023] Open
Abstract
BACKGROUND The African Great Lakes have long been recognized as an excellent location to study speciation. Most famously, cichlid fishes have radiated in Lake Tanganyika and subsequently spread into Lake Malawi and Lake Victoria, where they again radiated. Other taxa have diversified in these lakes, such as catfish, ostracods, gastropods, and Monegenean gill parasites of cichlids. However, these radiations have received less attention, and the process leading to their speciation in this unique region remains to be further explored. Here I present evidence that suggests a radiation of Macrostomum flatworms has occurred in the African Great Lakes region, offering a good opportunity for such investigations. RESULTS Recent field work has revealed a monophyletic clade of 16 Macrostomum flatworms that have, to date, only been collected from Lake Tanganyika. Additionally, a species collected from Lake Malawi was found nested within this clade. Molecular phylogenetic analysis, largely based on transcriptome data, suggests that this clade underwent rapid speciation, possibly due to a large habitat diversity in the lake. I also observed significant differences in the sperm morphology of these flatworms compared to those of species found outside Lake Tanganyika and Lake Malawi. These included the elongation of an anterior structure, a reduction in the size of the lateral sperm bristles, and changes in relative proportions. I propose functional hypotheses for these changes in sperm design, and formally describe Macrostomum gracilistylum sp. nov from Lake Malawi and its sister species Macrostomum crassum sp. nov., Macrostomum pellitum sp. nov., Macrostomum longispermatum sp. nov., and Macrostomum schäreri sp. nov., from Lake Tanganyika. CONCLUSIONS The available evidence is consistent with the hypothesis that Macrostomum flatworms have radiated in Lake Tanganyika and subsequently spread to Lake Malawi. However, whether this represents a bona fide adaptive radiation still needs to be determined. Therefore, the African Great Lakes are promising targets for further research into flatworm diversity and speciation.
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Affiliation(s)
- Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, Basel, 4051, Switzerland.
- Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Science, Am Fassberg 11, 37077, Göttingen, Germany.
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3
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Grosbusch AL, Bertemes P, Kauffmann B, Gotsis C, Egger B. Do Not Lose Your Head Over the Unequal Regeneration Capacity in Prolecithophoran Flatworms. BIOLOGY 2022; 11:1588. [PMID: 36358289 PMCID: PMC9687166 DOI: 10.3390/biology11111588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/20/2022] [Accepted: 10/27/2022] [Indexed: 10/21/2023]
Abstract
One of the central questions in studying the evolution of regeneration in flatworms remains whether the ancestral flatworm was able to regenerate all body parts, including the head. If so, this ability was subsequently lost in most existent flatworms. The alternative hypothesis is that head regeneration has evolved within flatworms, possibly several times independently. In the well-studied flatworm taxon Tricladida (planarians), most species are able to regenerate a head. Little is known about the regeneration capacity of the closest relatives of Tricladida: Fecampiida and Prolecithophora. Here, we analysed the regeneration capacity of three prolecithophoran families: Pseudostomidae, Plagiostomidae, and Protomonotresidae. The regeneration capacity of prolecithophorans varies considerably between families, which is likely related to the remaining body size of the regenerates. While all studied prolecithophoran species were able to regenerate a tail-shaped posterior end, only some Pseudostomidae could regenerate a part of the pharynx and pharynx pouch. Some Plagiostomidae could regenerate a head including the brain and eyes, provided the roots of the brain were present. The broad spectrum of regeneration capacity in Prolecithophora suggests that head regeneration capacity is not an apomorphy of Adiaphanida.
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Affiliation(s)
| | | | | | | | - Bernhard Egger
- Institute of Zoology, University of Innsbruck, 6020 Innsbruck, Austria
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Gordeev I, Biserova N, Zhukova K, Ekimova I. The first report of a parasitic 'turbellarian' from a cephalopod mollusc, with description of Octopoxenus antarcticus gen. nov., sp. nov. (Platyhelminthes: Fecampiida: Notenteridae). J Helminthol 2022; 96:e73. [PMID: 36250341 DOI: 10.1017/s0022149x22000657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Parasitic 'turbellarians' are known from various animals such as echinoderms, crustaceans, annelids, bivalve and gastropod molluscs. So far, however, no 'turbellarians' have been reported from cephalopods. In this paper we report a parasitic 'turbellarian' from the giant Antarctic octopus, Megaleledone setebos. We dissected two specimens of M. setebos caught in the Ross Sea (Antarctica) and found numerous worms in their intestine and liver. The worms were spherical or oblong and had two morphologically different poles. The frontal pole bears a small conical protrusion containing large elongated pear-shaped frontal glands and large polygonal cells. The ducts of the frontal glands open terminally to form the frontal organ. The caudal pole has an opening shaped as a folded tube connected by the genital pore with a common genital atrium, which continues into a canal with a muscular sheath. The worms were identified as 'turbellarians' from the family Notenteridae (Fecampiida). This family contains only one species, Notentera ivanovi, reported from the gut of a polychaete at the White Sea. The worms that we found in the gastrointestinal tract of the octopuses were morphologically similar to N. ivanovi but differed from it in several important respects. Phylogenetic analysis based on 28S rDNA gene showed that the newly found worm clustered together with other fecampiids in a highly supported clade and was closely related to N. ivanovi. On the basis of these morphological and molecular data, we described a new species, Octopoxenus antarcticus gen. nov., sp. nov. (Fecampiida: Notenteridae), establishing a new genus to accommodate it and provided an updated diagnosis of the family Notenteridae. This is the first report of a parasitic 'turbellarian' from a cephalopod mollusc.
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Affiliation(s)
- I Gordeev
- Russian Federal Research Institute of Fisheries and Oceanography, Moscow, Russia
- Lomonosov Moscow State University, Moscow, Russia
| | - N Biserova
- Lomonosov Moscow State University, Moscow, Russia
| | - K Zhukova
- Lomonosov Moscow State University, Moscow, Russia
| | - I Ekimova
- Lomonosov Moscow State University, Moscow, Russia
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Shi Y, Zeng Z, Wang J, Zhang S, Deng L, Wang A. Three new species of Macrostomum (Platyhelminthes, Macrostomorpha) from China and Australia, with notes on taxonomy and phylogenetics. Zookeys 2022; 1099:1-28. [PMID: 36761444 PMCID: PMC9848920 DOI: 10.3897/zookeys.1099.72964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 03/31/2022] [Indexed: 11/12/2022] Open
Abstract
In this paper, three species of the macrostomid free-living flatworm genus Macrostomum are described. Two species, Macrostomumlittorale Wang & Shi, sp. nov. and M.shekouense Wang & Shi, sp. nov., were collected from coastal water at Shenzhen, Guangdong Province, China. One species, M.brandi Wang & Shi, sp. nov., was collected from Perth, Western Australia and Queenscliff, Victoria, Australia. Macrostomumlittorale sp. nov. differs from congeneric species within the genus in the length of the stylet, diameter of stylet opening, and the bend of the stylet. Macrostomumshekouense sp. nov. and M.brandi sp. nov. differ from similar species within the genus in the stylet morphology, position of the female antrum and developing eggs, or presence or absence of the false seminal vesicle. Phylogenetic analysis based on cytochrome c oxidase subunit I (COI) gene shows that M.littorale sp. nov. and M.hystrix are sister clades on two well-separated branch, M.shekouense sp. nov. and M.brandi sp. nov. are sister clades on two well-separated branches. Accordingly, both morphological and molecular evidence support M.littorale sp. nov., M.shekouense sp. nov., and M.brandi sp. nov. as three new species.
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Affiliation(s)
- Yongshi Shi
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Zhiyu Zeng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Jia Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Siyu Zhang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Li Deng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Antai Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
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Brand JN, Harmon LJ, Schärer L. Mating behavior and reproductive morphology predict macroevolution of sex allocation in hermaphroditic flatworms. BMC Biol 2022; 20:35. [PMID: 35130880 PMCID: PMC8822660 DOI: 10.1186/s12915-022-01234-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/18/2022] [Indexed: 11/10/2022] Open
Abstract
Background Sex allocation is the distribution of resources to male or female reproduction. In hermaphrodites, this concerns an individual’s resource allocation to, for example, the production of male or female gametes. Macroevolutionary studies across hermaphroditic plants have revealed that the self-pollination rate and the pollination mode are strong predictors of sex allocation. Consequently, we expect similar factors such as the selfing rate and aspects of the reproductive biology, like the mating behaviour and the intensity of postcopulatory sexual selection, to predict sex allocation in hermaphroditic animals. However, comparative work on hermaphroditic animals is limited. Here, we study sex allocation in 120 species of the hermaphroditic free-living flatworm genus Macrostomum. We ask how hypodermic insemination, a convergently evolved mating behaviour where sperm are traumatically injected through the partner’s epidermis, affects the evolution of sex allocation. We also test the commonly-made assumption that investment into male and female reproduction should trade-off. Finally, we ask if morphological indicators of the intensity of postcopulatory sexual selection (female genital complexity, male copulatory organ length, and sperm length) can predict sex allocation. Results We find that the repeated evolution of hypodermic insemination predicts a more female-biased sex allocation (i.e., a relative shift towards female allocation). Moreover, transcriptome-based estimates of heterozygosity reveal reduced heterozygosity in hypodermically mating species, indicating that this mating behavior is linked to increased selfing or biparental inbreeding. Therefore, hypodermic insemination could represent a selfing syndrome. Furthermore, across the genus, allocation to male and female gametes is negatively related, and larger species have a more female-biased sex allocation. Finally, increased female genital complexity, longer sperm, and a longer male copulatory organ predict a more male-biased sex allocation. Conclusions Selfing syndromes have repeatedly originated in plants. Remarkably, this macroevolutionary pattern is replicated in Macrostomum flatworms and linked to repeated shifts in reproductive behavior. We also find a trade-off between male and female reproduction, a fundamental assumption of most theories of sex allocation. Beyond that, no theory predicts a more female-biased allocation in larger species, suggesting avenues for future work. Finally, morphological indicators of more intense postcopulatory sexual selection appear to predict more intense sperm competition. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-022-01234-1.
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Affiliation(s)
- Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland. .,Department of Tissue Dynamics and Regeneration, Max Planck Institute for Multidisciplinary Sciences, Am Fassberg 11, 37077, Göttingen, Germany.
| | - Luke J Harmon
- Department of Biological Sciences, University of Idaho, Life Sciences South 252, 875 Perimeter Dr MS 3051, Moscow, ID, USA
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
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7
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Brand JN, Harmon LJ, Schärer L. Frequent origins of traumatic insemination involve convergent shifts in sperm and genital morphology. Evol Lett 2022; 6:63-82. [PMID: 35127138 PMCID: PMC8802240 DOI: 10.1002/evl3.268] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
Traumatic insemination is a mating behavior during which the (sperm) donor uses a traumatic intromittent organ to inject an ejaculate through the epidermis of the (sperm) recipient, thereby frequently circumventing the female genitalia. Traumatic insemination occurs widely across animals, but the frequency of its evolution, the intermediate stages via which it originates, and the morphological changes that such shifts involve remain poorly understood. Based on observations in 145 species of the free-living flatworm genus Macrostomum, we identify at least nine independent evolutionary origins of traumatic insemination from reciprocal copulation, but no clear indication of reversals. These origins involve convergent shifts in multivariate morphospace of male and female reproductive traits, suggesting that traumatic insemination has a canalizing effect on morphology. We also observed sperm in both the sperm receiving organ and within the body tissue of two species. These species had intermediate trait values indicating that traumatic insemination evolves through initial internal wounding during copulation. Finally, signatures of male-female coevolution of genitalia across the genus indicate that sexual selection and sexual conflict drive the evolution of traumatic insemination, because it allows donors to bypass postcopulatory control mechanisms of recipients.
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Affiliation(s)
- Jeremias N. Brand
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
- Department of Tissue Dynamics and RegenerationMax Planck Institute for Biophysical ChemistryGöttingenDE‐37077Germany
| | - Luke J. Harmon
- Department of Biological SciencesUniversity of IdahoMoscowIdaho83843
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
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Wiberg RAW, Brand JN, Schärer L. Faster Rates of Molecular Sequence Evolution in Reproduction-Related Genes and in Species with Hypodermic Sperm Morphologies. Mol Biol Evol 2021; 38:5685-5703. [PMID: 34534329 PMCID: PMC8662610 DOI: 10.1093/molbev/msab276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sexual selection drives the evolution of many striking behaviors and morphologies and should leave signatures of selection at loci underlying these phenotypes. However, although loci thought to be under sexual selection often evolve rapidly, few studies have contrasted rates of molecular sequence evolution at such loci across lineages with different sexual selection contexts. Furthermore, work has focused on separate sexed animals, neglecting alternative sexual systems. We investigate rates of molecular sequence evolution in hermaphroditic flatworms of the genus Macrostomum. Specifically, we compare species that exhibit contrasting sperm morphologies, strongly associated with multiple convergent shifts in the mating strategy, reflecting different sexual selection contexts. Species donating and receiving sperm in every mating have sperm with bristles, likely to prevent sperm removal. Meanwhile, species that hypodermically inject sperm lack bristles, potentially as an adaptation to the environment experienced by hypodermic sperm. Combining functional annotations from the model, Macrostomum lignano, with transcriptomes from 93 congeners, we find genus-wide faster sequence evolution in reproduction-related versus ubiquitously expressed genes, consistent with stronger sexual selection on the former. Additionally, species with hypodermic sperm morphologies had elevated molecular sequence evolution, regardless of a gene's functional annotation. These genome-wide patterns suggest reduced selection efficiency following shifts to hypodermic mating, possibly due to higher selfing rates in these species. Moreover, we find little evidence for convergent amino acid changes across species. Our work not only shows that reproduction-related genes evolve rapidly also in hermaphroditic animals, but also that well-replicated contrasts of different sexual selection contexts can reveal underappreciated genome-wide effects.
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Affiliation(s)
- R Axel W Wiberg
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
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Carbayo F, Marian JEAR. Morphology of parenchymally implanted foreign bodies indicates copulatory wounding in a planarian. J Morphol 2021; 282:1765-1771. [PMID: 34609011 DOI: 10.1002/jmor.21418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/23/2021] [Accepted: 09/29/2021] [Indexed: 11/08/2022]
Abstract
Traumatic mating, that is, copulation that involves wounding the partner's body, is a widespread phenomenon that is particularly prevalent in hermaphroditic animals. Traumatic mating is generally a collateral side effect of diverse strategies (from physical anchorage to injection of substances to manipulate the partner), but the trauma could also be adaptive by itself if it delays remating by the injured partner. In the Tricladida (the clade of planarian flatworms), reciprocal sperm transfer is often assumed to occur by means of a 'regular' nontraumatic copulation, that is, insertion of the penis through the partner's gonopore and deposition of the ejaculate into its genital atrium, with subsequent sperm migration to the oviducts. However, while studying the anatomy of Brazilian land planarians for taxonomic purposes, we found foreign bodies, reminiscent of spermatophores, implanted within the parenchyma of Choeradoplana albonigra (Riester, 1938). Herein, we describe and illustrate several lines of morphological evidence indicating that these foreign bodies likely represent a novel case of intragenital copulatory wounding (e.g., structural and histochemical similarity to land planarians spermatophores; implantation at the level of the gonopore; vestiges of rupture of the genital atrium's wall), corroborating that traumatic mating is pervasive and underreported in Metazoa. We also propose two different hypotheses to explain such copulatory wounding, viz., that it concerns (1) a regular mating strategy or (2) an accidental effect of the copulation. In any event, this land planarian may prove useful as a novel, noninsect terrestrial model organism to investigate the evolution of traumatic mating.
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Affiliation(s)
- Fernando Carbayo
- Laboratório de Ecologia e Evolução, Escola de Artes, Ciências e Humanidades (EACH), Universidade de São Paulo (USP), São Paulo, SP, Brazil
| | - José E A R Marian
- Departamento de Zoologia, Instituto de Biociências (IB), Universidade de São Paulo (USP), São Paulo, Brazil
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Large-scale phylogenomics of the genus Macrostomum (Platyhelminthes) reveals cryptic diversity and novel sexual traits. Mol Phylogenet Evol 2021; 166:107296. [PMID: 34438051 DOI: 10.1016/j.ympev.2021.107296] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/01/2021] [Accepted: 08/19/2021] [Indexed: 02/07/2023]
Abstract
Free-living flatworms of the genus Macrostomum are small and transparent animals, representing attractive study organisms for a broad range of topics in evolutionary, developmental, and molecular biology. The genus includes the model organism M. lignano for which extensive molecular resources are available, and recently there is a growing interest in extending work to additional species in the genus. These endeavours are currently hindered because, even though >200 Macrostomum species have been taxonomically described, molecular phylogenetic information and geographic sampling remain limited. We report on a global sampling campaign aimed at increasing taxon sampling and geographic representation of the genus. Specifically, we use extensive transcriptome and single-locus data to generate phylogenomic hypotheses including 145 species. Across different phylogenetic methods and alignments used, we identify several consistent clades, while their exact grouping is less clear, possibly due to a radiation early in Macrostomum evolution. Moreover, we uncover a large undescribed diversity, with 94 of the studied species likely being new to science, and we identify multiple novel morphological traits. Furthermore, we identify cryptic speciation in a taxonomically challenging assemblage of species, suggesting that the use of molecular markers is a prerequisite for future work, and we describe the distribution of putative synapomorphies and suggest taxonomic revisions based on our finding. Our large-scale phylogenomic dataset now provides a robust foundation for comparative analyses of morphological, behavioural and molecular evolution in this genus.
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Zhang S, Shi Y, Zeng Z, Xin F, Deng L, Wang A. Two New Brackish-Water Species of Macrostomum (Platyhelminthes: Macrostomorpha) from China and Their Phylogenetic Positions. Zoolog Sci 2021; 38:273-286. [PMID: 34057353 DOI: 10.2108/zs200121] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 12/15/2020] [Indexed: 11/17/2022]
Abstract
In this paper, two new brackish-water species of the macrostomid turbellarian genus Macrostomum, Macrostomum pseudosinense sp. nov. and Macrostomum taurinum sp. nov., collected from coastal water at Shenzhen, Guangdong Province, China, are described based on morphological, histological, and molecular phylogenetic analyses. Macrostomum pseudosinense sp. nov. differs from similar species within the genus in the length of the stylet (152 ± 15.0 µm), diameter of stylet opening (20 ± 4.0 µm proximally; 7 ± 0.5 µm distally), two bends of the stylet, and the non-spiral end of the stylet. Macrostomum taurinum sp. nov. differs from its congeners in the length of the stylet (81 ± 7.4 µm), the stylet bending position and angle (50% and 60°), diameter of stylet proximal opening (15 ± 3.0 µm), sperm with bristles and brush, and the smooth-walled ovaries. Phylogenetic analyses inferred from nuclear 18S and 28S rRNA genes support the establishments of these two new species. In addition, reciprocal mating behavior of M. pseudosinense sp. nov. was observed and documented.
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Affiliation(s)
- Siyu Zhang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China
| | - Yongshi Shi
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China
| | - Zicheng Zeng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China
| | - Fan Xin
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China
| | - Li Deng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China,
| | - Antai Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, PR China,
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12
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Curini-Galletti M, Artois T, Di Domenico M, Fontaneto D, Jondelius U, Jörger KM, Leasi F, Martínez A, Norenburg JL, Sterrer W, Todaro MA. Contribution of soft-bodied meiofaunal taxa to Italian marine biodiversity. THE EUROPEAN ZOOLOGICAL JOURNAL 2020. [DOI: 10.1080/24750263.2020.1786607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Affiliation(s)
- M. Curini-Galletti
- Dipartimento di Medicina Veterinaria, Università di Sassari, Sassari, Italy
| | - T. Artois
- Research Group Zoology: Biodiversity & Toxicology, Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | - M. Di Domenico
- Center for Marine Studies, Universidade Federal do Paraná, Curitiba, Brazil
| | - D. Fontaneto
- Molecular Ecology Group, Water Research Institute - CNR, Verbania, Italy
| | - U. Jondelius
- Department of Invertebrate Zoology, Swedish Museum of Natural History, Stockholm, Sweden
| | - K. M. Jörger
- SNSB-Bavarian State Collection of Zoology, Munich, Germany
| | - F. Leasi
- Department of Biology, Geology and Environmental Science, University of Tennessee, Chattanooga, TN, USA
| | - A. Martínez
- Molecular Ecology Group, Water Research Institute - CNR, Verbania, Italy
| | - J. L. Norenburg
- Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution (USA), Washington, DC, USA
| | | | - M. A. Todaro
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Modena, Italy
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13
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Brand JN, Wiberg RAW, Pjeta R, Bertemes P, Beisel C, Ladurner P, Schärer L. RNA-Seq of three free-living flatworm species suggests rapid evolution of reproduction-related genes. BMC Genomics 2020; 21:462. [PMID: 32631219 PMCID: PMC7336406 DOI: 10.1186/s12864-020-06862-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 06/22/2020] [Indexed: 01/03/2023] Open
Abstract
Background The genus Macrostomum consists of small free-living flatworms and contains Macrostomum lignano, which has been used in investigations of ageing, stem cell biology, bioadhesion, karyology, and sexual selection in hermaphrodites. Two types of mating behaviour occur within this genus. Some species, including M. lignano, mate via reciprocal copulation, where, in a single mating, both partners insert their male copulatory organ into the female storage organ and simultaneously donate and receive sperm. Other species mate via hypodermic insemination, where worms use a needle-like copulatory organ to inject sperm into the tissue of the partner. These contrasting mating behaviours are associated with striking differences in sperm and copulatory organ morphology. Here we expand the genomic resources within the genus to representatives of both behaviour types and investigate whether genes vary in their rate of evolution depending on their putative function. Results We present de novo assembled transcriptomes of three Macrostomum species, namely M. hystrix, a close relative of M. lignano that mates via hypodermic insemination, M. spirale, a more distantly related species that mates via reciprocal copulation, and finally M. pusillum, which represents a clade that is only distantly related to the other three species and also mates via hypodermic insemination. We infer 23,764 sets of homologous genes and annotate them using experimental evidence from M. lignano. Across the genus, we identify 521 gene families with conserved patterns of differential expression between juvenile vs. adult worms and 185 gene families with a putative expression in the testes that are restricted to the two reciprocally mating species. Further, we show that homologs of putative reproduction-related genes have a higher protein divergence across the four species than genes lacking such annotations and that they are more difficult to identify across the four species, indicating that these genes evolve more rapidly, while genes involved in neoblast function are more conserved. Conclusions This study improves the genus Macrostomum as a model system, by providing resources for the targeted investigation of gene function in a broad range of species. And we, for the first time, show that reproduction-related genes evolve at an accelerated rate in flatworms.
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Affiliation(s)
- Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.
| | - R Axel W Wiberg
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Robert Pjeta
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Philip Bertemes
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Christian Beisel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel, Switzerland
| | - Peter Ladurner
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
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14
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Balsamo M, Artois T, Smith JPS, Todaro MA, Guidi L, Leander BS, Van Steenkiste NWL. The curious and neglected soft-bodied meiofauna: Rouphozoa (Gastrotricha and Platyhelminthes). HYDROBIOLOGIA 2020; 847:2613-2644. [PMID: 33551466 PMCID: PMC7864459 DOI: 10.1007/s10750-020-04287-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 04/25/2020] [Accepted: 05/04/2020] [Indexed: 06/11/2023]
Abstract
Gastrotricha and Platyhelminthes form a clade called Rouphozoa. Representatives of both taxa are main components of meiofaunal communities, but their role in the trophic ecology of marine and freshwater communities is not sufficiently studied. Traditional collection methods for meiofauna are optimized for Ecdysozoa, and include the use of fixatives or flotation techniques that are unsuitable for the preservation and identification of soft-bodied meiofauna. As a result, rouphozoans are usually underestimated in conventional biodiversity surveys and ecological studies. Here, we give an updated outline of their diversity and taxonomy, with some phylogenetic considerations. We describe successfully tested techniques for their recovery and study, and emphasize current knowledge on the ecology, distribution and dispersal of freshwater gastrotrichs and microturbellarians. We also discuss the opportunities and pitfalls of (meta)barcoding studies as a means of overcoming the taxonomic impediment. Finally, we discuss the importance of rouphozoans in aquatic ecosystems and provide future research directions to fill in crucial gaps in the biology of these organisms needed for understanding their basic role in the ecology of benthos and their place in the trophic networks linking micro-, meio- and macrofauna of freshwater ecosystems.
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Affiliation(s)
- Maria Balsamo
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Tom Artois
- Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium
| | | | - M Antonio Todaro
- Department of Life Sciences, University of Modena-Reggio Emilia, Modena, Italy
| | - Loretta Guidi
- Department of Biomolecular Sciences, University of Urbino, Urbino, Italy
| | - Brian S Leander
- Departments of Botany and Zoology, University of British Columbia, Vancouver, BC, Canada
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15
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Schärer L, Brand JN, Singh P, Zadesenets KS, Stelzer C, Viktorin G. A phylogenetically informed search for an alternative
Macrostomum
model species, with notes on taxonomy, mating behavior, karyology, and genome size. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12344] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Lukas Schärer
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Jeremias N. Brand
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Pragya Singh
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Kira S. Zadesenets
- The Federal Research Center Institute of Cytology and Genetics SB RAS Novosibirsk Russia
| | | | - Gudrun Viktorin
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
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16
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Mitsi K, Arroyo AS, Ruiz-Trillo I. A global metabarcoding analysis expands molecular diversity of Platyhelminthes and reveals novel early-branching clades. Biol Lett 2019; 15:20190182. [PMID: 31506037 PMCID: PMC6769146 DOI: 10.1098/rsbl.2019.0182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 08/14/2019] [Indexed: 01/29/2023] Open
Abstract
Understanding biological diversity is crucial for ecological and evolutionary studies. Even though a great part of animal diversity has already been documented, both morphological surveys and metabarcoding analyses have previously shown that some animal groups, such as Platyhelminthes, may harbour hidden diversity. To better understand the molecular diversity of Platyhelminthes, one of the most diverse and biomedically important animal phyla, we here combined data from six marine and two freshwater metabarcoding expeditions that cover a broad variety of aquatic habitats and analysed the data by phylogenetic placement. Our results show that a great part of the hidden diversity is located in early-branching clades such as Catenulida and Macrostomorpha, as well as in late-diverging clades such as Proseriata and Rhabdocoela. We also report the first freshwater record of Gnosonesimida, a group previously thought to be exclusively marine. Finally, we identified two putative novel freshwater Platyhelminthes clades that branch between well-defined orders of the phylum. Thus, our analyses of several environmental datasets confirm that a large part of the diversity of Platyhelminthes remains undiscovered, point to groups with more potential novel species and identify freshwater environments as potential reservoirs for novel species of flatworms.
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Affiliation(s)
- Konstantina Mitsi
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Catalonia, Spain
| | - Alicia S. Arroyo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Catalonia, Spain
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003, Catalonia, Spain
- Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona (UB), Barcelona 08028, Catalonia, Spain
- ICREA, Pg. Lluís Companys 23, Barcelona 08010, Catalonia, Spain
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17
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Dittmann IL, Cuadrado D, Aguado MT, Noreña C, Egger B. Polyclad phylogeny persists to be problematic. ORG DIVERS EVOL 2019. [DOI: 10.1007/s13127-019-00415-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Abstract
Two conflicting morphological approaches to polyclad systematics highlight the relevance of molecular data for resolving the interrelationships of Polycladida. In the present study, phylogenetic trees were reconstructed based on a short alignment of the 28S rDNA marker gene with 118 polyclad terminals (24 new) including 100 different polyclad species from 44 genera and 22 families, as well as on a combined dataset using 18S and 28S rDNA genes with 27 polyclad terminals (19 new) covering 26 different polyclad species. In both approaches, Theamatidae and Cestoplanidae were included, two families that have previously been shown to switch from Acotylea to Cotylea. Three different alignment methods were used, both with and without alignment curation by Gblocks, and all alignments were subjected to Bayesian inference and maximum likelihood tree calculations. Over all trees of the combined dataset, an extended majority-rule consensus tree had weak support for Theamatidae and Cestoplanidae as acotyleans, and also the cotylean genera Boninia, Chromyella and Pericelis appeared as acotyleans. With the most inclusive short 28S dataset, on the other hand, there is good support for the aforementioned taxa as cotyleans. Especially with the short 28S matrix, taxon sampling, outgroup selection, alignment method and curation, as well as model choice were all decisive for tree topology. Well-supported parts of the phylogeny over all trees include Pseudocerotoidea, Prosthiostomoidea, Stylochoidea, Leptoplanoidea and Cryptoceloidea, the latter three with new definitions. Unstable positions in the tree were found not only for Theamatidae, Cestoplanidae, Boninia, Chromyella and Pericelis, but also for Anonymus, Chromoplana and Cycloporus.
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18
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Atherton S, Jondelius U. A taxonomic review and revisions of Microstomidae (Platyhelminthes: Macrostomorpha). PLoS One 2019; 14:e0212073. [PMID: 31017906 PMCID: PMC6481776 DOI: 10.1371/journal.pone.0212073] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/22/2019] [Indexed: 11/18/2022] Open
Abstract
Microstomidae (Platyhelminthes: Macrostomorpha) diversity has been almost entirely ignored within recent years, likely due to inconsistent and often old taxonomic literature and a general rarity of sexually mature collected specimens. Herein, we reconstruct the phylogenetic relationships of the group using both previously published and new 18S and CO1 gene sequences. We present some taxonomic revisions of Microstomidae and further describe 8 new species of Microstomum based on both molecular and morphological evidence. Finally, we briefly review the morphological taxonomy of each species and provide a key to aid in future research and identification that is not dependent on reproductive morphology. Our goal is to clarify the taxonomy and facilitate future research into an otherwise very understudied group of tiny (but important) flatworms.
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Affiliation(s)
- Sarah Atherton
- Department of Zoology, Naturhistoriska riksmuseet, Stockholm, Sweden
| | - Ulf Jondelius
- Department of Zoology, Naturhistoriska riksmuseet, Stockholm, Sweden
- Department of Zoology, Systematics and Evolution, Stockholms Universitet,Stockholm, Sweden
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19
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Sekii K, Yorimoto S, Okamoto H, Nagao N, Maezawa T, Matsui Y, Yamaguchi K, Furukawa R, Shigenobu S, Kobayashi K. Transcriptomic analysis reveals differences in the regulation of amino acid metabolism in asexual and sexual planarians. Sci Rep 2019; 9:6132. [PMID: 30992461 PMCID: PMC6467871 DOI: 10.1038/s41598-019-42025-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 03/22/2019] [Indexed: 12/25/2022] Open
Abstract
Many flatworms can alternate between asexual and sexual reproduction. This is a powerful reproductive strategy enabling them to benefit from the features of the two reproductive modes, namely, rapid multiplication and genetic shuffling. The two reproductive modes are enabled by the presence of pluripotent adult stem cells (neoblasts), by generating any type of tissue in the asexual mode, and producing and maintaining germ cells in the sexual mode. In the current study, RNA sequencing (RNA-seq) was used to compare the transcriptomes of two phenotypes of the planarian Dugesia ryukyuensis: an asexual OH strain and an experimentally sexualized OH strain. Pathway enrichment analysis revealed striking differences in amino acid metabolism in the two worm types. Further, the analysis identified serotonin as a new bioactive substance that induced the planarian ovary de novo in a postembryonic manner. These findings suggest that different metabolic states and physiological conditions evoked by sex-inducing substances likely modulate stem cell behavior, depending on their different function in the asexual and sexual reproductive modes. The combination of RNA-seq and a feeding assay in D. ryukyuensis is a powerful tool for studying the alternation of reproductive modes, disentangling the relationship between gene expression and chemical signaling molecules.
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Affiliation(s)
- Kiyono Sekii
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8561, Japan
| | - Shunta Yorimoto
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8561, Japan
| | - Hikaru Okamoto
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8561, Japan
| | - Nanna Nagao
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8561, Japan
| | - Takanobu Maezawa
- Department of Integrated Science and Technology, National Institute of Technology, Tsuyama College, 624-1 Numa, Tsuyama, Okayama, 708-8509, Japan
| | - Yasuhisa Matsui
- Cell Resource Center for Biomedical Research, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Sendai, 980-8575, Japan
| | - Katsushi Yamaguchi
- NIBB Core Research Facilities, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki, 444-8585, Japan
| | - Ryohei Furukawa
- Division of Biomedical Information Analysis, Iwate Tohoku Medical Megabank Organization, Iwate Medical University, 2-1-1 Nishitokuda, Yanaba-cho, Shiwa-gun, Iwate, 028-3694, Japan. .,Department of Biology, Research and Education Center for Natural Sciences, Keio University, 4-1-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa, 223-8521, Japan.
| | - Shuji Shigenobu
- NIBB Core Research Facilities, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki, 444-8585, Japan. .,Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka Myodaiji, Okazaki, 444-8585, Japan.
| | - Kazuya Kobayashi
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori, 036-8561, Japan.
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20
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21
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New insights into the genital musculature of Macrostomum johni (Platyhelminthes, Macrostomorpha), revealed with CLSM. ZOOL ANZ 2018. [DOI: 10.1016/j.jcz.2018.04.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Atherton S, Jondelius U. Wide distributions and cryptic diversity within a Microstomum
(Platyhelminthes) species complex. ZOOL SCR 2018. [DOI: 10.1111/zsc.12290] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sarah Atherton
- Department of Zoology; Naturhistoriska riksmuseet; Stockholm Sweden
| | - Ulf Jondelius
- Department of Zoology; Naturhistoriska riksmuseet; Stockholm Sweden
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23
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Dolmatov IY, Afanasyev SV, Boyko AV. Molecular mechanisms of fission in echinoderms: Transcriptome analysis. PLoS One 2018; 13:e0195836. [PMID: 29649336 PMCID: PMC5897022 DOI: 10.1371/journal.pone.0195836] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 04/01/2018] [Indexed: 12/11/2022] Open
Abstract
Echinoderms are capable of asexual reproduction by fission. An individual divides into parts due to changes in the strength of connective tissue of the body wall. The structure of connective tissue and the mechanisms of variations in its strength in echinoderms remain poorly studied. An analysis of transcriptomes of individuals during the process of fission provides a new opportunity to understand the mechanisms of connective tissue mutability. In the holothurian Cladolabes schmeltzii, we have found a rather complex organization of connective tissue. Transcripts of genes encoding a wide range of structural proteins of extracellular matrix, as well as various proteases and their inhibitors, have been discovered. All these molecules may constitute a part of the mechanism of connective tissue mutability. According to our data, the extracellular matrix of echinoderms is substantially distinguished from that of vertebrates by the lack of elastin, fibronectins, and tenascins. In case of fission, a large number of genes of transcription factors and components of different signaling pathways are expressed. Products of these genes are probably involved in regulation of asexual reproduction, connective tissue mutability, and preparation of tissues for subsequent regeneration. It has been shown that holothurian tensilins are a special group of tissue inhibitors of metalloproteinases, which has formed within the class Holothuroidea and is absent from other echinoderms. Our data can serve a basis for the further study of the mechanisms of extracellular matrix mutability, as well as the mechanisms responsible for asexual reproduction in echinoderms.
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Affiliation(s)
- Igor Yu. Dolmatov
- A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
- Far Eastern Federal University, Vladivostok, Russia
- * E-mail:
| | - Sergey V. Afanasyev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Saint Petersburg, Russia
| | - Alexey V. Boyko
- A.V. Zhirmunsky Institute of Marine Biology, National Scientific Center of Marine Biology, Far Eastern Branch, Russian Academy of Sciences, Vladivostok, Russia
- Far Eastern Federal University, Vladivostok, Russia
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24
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Poddubnaya LG, Hemmingsen W, Bruñanská M, Gibson DI. Ultrastructural characteristics of the male ducts and terminal genitalia of an endoparasitic monogenean, Calicotyle affinis Scott, 1911 (Monopisthocotylea: Monocotylidae), with the first detailed description of a copulatory stylet in a monogenean. Parasitol Res 2018; 117:1503-1512. [DOI: 10.1007/s00436-018-5831-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/06/2018] [Indexed: 11/29/2022]
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25
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Zadesenets KS, Schärer L, Rubtsov NB. New insights into the karyotype evolution of the free-living flatworm Macrostomum lignano (Platyhelminthes, Turbellaria). Sci Rep 2017; 7:6066. [PMID: 28729552 PMCID: PMC5519732 DOI: 10.1038/s41598-017-06498-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 06/13/2017] [Indexed: 01/02/2023] Open
Abstract
The free-living flatworm Macrostomum lignano is a model organism for evolutionary and developmental biology studies. Recently, an unusual karyotypic diversity was revealed in this species. Specifically, worms are either ‘normal’ 2n = 8, or they are aneuploid with one or two additional large chromosome(s) (i.e. 2n = 9 or 2n = 10, respectively). Aneuploid worms did not show visible behavioral or morphological abnormalities and were successful in reproduction. In this study, we generated microdissected DNA probes from chromosome 1 (further called MLI1), chromosome 2 (MLI2), and a pair of similar-sized smaller chromosomes (MLI3, MLI4). FISH using these probes revealed that MLI1 consists of contiguous regions homologous to MLI2-MLI4, suggesting that MLI1 arose due to the whole genome duplication and subsequent fusion of one full chromosome set into one large metacentric chromosome. Therefore, one presumably full haploid genome was packed into MLI1, leading to hidden tetraploidy in the M. lignano genome. The study of Macrostomum sp. 8 — a sibling species of M. lignano — revealed that it usually has one additional pair of large chromosomes (2n = 10) showing a high homology to MLI1, thus suggesting hidden hexaploidy in its genome. Possible evolutionary scenarios for the emergence of the M. lignano and Macrostomum sp. 8 genomes are discussed.
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Affiliation(s)
- Kira S Zadesenets
- The Federal Research Center Institute of Cytology and Genetics SB RAS, Lavrentiev ave., 10, Novosibirsk, 630090, Russian Federation.
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, CH-4051, Switzerland
| | - Nikolay B Rubtsov
- The Federal Research Center Institute of Cytology and Genetics SB RAS, Lavrentiev ave., 10, Novosibirsk, 630090, Russian Federation.,Novosibirsk State University, Pirogova str., 2, Novosibirsk, 630090, Russian Federation
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26
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Bahia J, Padula V, Schrödl M. Polycladida phylogeny and evolution: integrating evidence from 28S rDNA and morphology. ORG DIVERS EVOL 2017. [DOI: 10.1007/s13127-017-0327-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Giannakara A, Ramm SA. Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically inseminating flatworm Macrostomum pusillum. ACTA ACUST UNITED AC 2017; 220:1568-1577. [PMID: 28183866 DOI: 10.1242/jeb.149682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/03/2017] [Indexed: 01/15/2023]
Abstract
The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra- and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomumpusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.
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Affiliation(s)
- Athina Giannakara
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
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28
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Zadesenets KS, Vizoso DB, Schlatter A, Konopatskaia ID, Berezikov E, Schärer L, Rubtsov NB. Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology. PLoS One 2016; 11:e0164915. [PMID: 27755577 PMCID: PMC5068713 DOI: 10.1371/journal.pone.0164915] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 10/03/2016] [Indexed: 11/19/2022] Open
Abstract
Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.
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Affiliation(s)
- Kira S. Zadesenets
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
- * E-mail:
| | - Dita B. Vizoso
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| | - Aline Schlatter
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| | | | - Eugene Berezikov
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| | - Nikolay B. Rubtsov
- Institute of Cytology and Genetics SB RAS, Novosibirsk, Russian Federation
- Novosibirsk State University, Novosibirsk, Russian Federation
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Ramm SA, Schlatter A, Poirier M, Schärer L. Hypodermic self-insemination as a reproductive assurance strategy. Proc Biol Sci 2016; 282:rspb.2015.0660. [PMID: 26136446 DOI: 10.1098/rspb.2015.0660] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Self-fertilization occurs in a broad range of hermaphroditic plants and animals, and is often thought to evolve as a reproductive assurance strategy under ecological conditions that disfavour or prevent outcrossing. Nevertheless,selfing ability is far from ubiquitous among hermaphrodites, and may be constrained in taxa where the male and female gametes of the same individual cannot easily meet. Here, we report an extraordinary selfing mechanism in one such species, the free-living flatworm Macrostomum hystrix. To test the hypothesis that adaptations to hypodermic insemination of the mating partner under outcrossing also facilitate selfing, we experimentally manipulated the social environment of these transparent flatworms and then observed the spatial distribution of received sperm in vivo. We find that this distribution differs radically between conditions allowing or preventing outcrossing, implying that isolated individuals use their needle-like stylet (male copulatory organ) to inject own sperm into their anterior body region, including into their own head, from where they then apparently migrate to the site of (self-)fertilization. Conferring the ability to self could thus be an additional consequence of hypodermic insemination, a widespread fertilization mode that is especially prevalent among simultaneously hermaphroditic animals and probably evolves due to sexual conflict over the transfer and subsequent fate of sperm.
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